1. Field of the Invention
The present invention relates generally to focusing control for obtaining a detected image used for image authentication that determines on whether the detected image represents the authentic person or another person by a process of detecting the features of a living body expressed in fingerprints or veins in the form of an image and comparing the detected image with a recorded image, and, more particularly, to an image authenticating apparatus, an image authenticating method, an image authenticating program, a recording medium, an electronic device, and a circuit substrate that guide a portion to be detected to a recommended position for image capturing to take in a detected image.
2. Description of the Related Art
In conventional image authentication on the veins of a palm to determine on whether the palm belongs to an authentic person or another person, a recoded image RI, as shown in FIG. 23(A), is compared with a detected image SI, as shown in FIG. 23(B), and whether the detected image SI matches the recorded image RI is determined. In such image authentication, for example, an image of the palm to be authenticated is captured by applying near-infrared rays to the palm and causing the rays to reflect on the palm to obtain a vein image that shows the position and form of the veins through the intensity/weakness of the reflected infrared rays. This vein image is used as a recorded image and as a detected image. The form of veins, like the same of fingerprints, retinas, face, DNA, etc., is suitable for being handled as identification data of an individual, thus used for individual authentication.
Regarding with such image authentication, Japanese Patent Application Laid-Open Publication No. 2001-326841 discloses a technique that a range for executing palm print recognition is exhibited on a display while a frame showing the outer edge of the recognition range is also exhibited on the display to clearly demonstrate the recognition range, and that a distance between a camera and a palm is adjusted (paragraph numbers 0038, 0039, 0040, FIG. 4, FIG. 6, etc.). Japanese Patent Application Laid-Open Publication No. 1999-47119 discloses a technique that a ring for preventing a left/right or back/forth shift of a hand to be detected is provided to position the hand relative to a detection terminal (paragraph numbers 0048 to 0050, ABSTRACT, FIG. 4, FIG. 5, etc.).
According to the technique disclosed in Japanese Patent Application Laid-Open Publication No. 2001-326841, while the frame showing the outer edge of the recognition range is exhibited on the display, a person requesting living body authentication still have to go through extreme cumbersome operations of minding the frame as the recognition range and adjusting the distance between a camera and the palm before obtaining a proper image. On the other hand, the technique disclosed in Japanese Patent Application Laid-Open Publication No. 1999-47119 restricts the degree of freedom of the hand to be detected, if in a moment, thus raising a concern of giving a person requesting authentication an unpleasant feeling.
FIG. 24 depicts an automated teller machine (ATM) 400 provided with an image-capturing device 404 adjacent to a customer operating panel 402, which image-capturing device 404 captures an image of a palm of a user. The image-capturing device 404 has a sensor guide 408 attached to the front face of a sensor unit 406, where the sensor guide 408 guides the palm of the user to the sensor unit 406. This sensor guide 408 is so constructed that the user puts his or her wrist on a flat portion 410 of the sensor guide 408 to locate the palm for image capturing at an image-capturing position on the sensor unit 406. The image-capturing device 404, however, has such a disadvantage that the positioning sensor guide 408 projects out of the image-capturing device 404, and that the palm may not be set at an optimum position even if the writs is kept supported on the sensor guide 408 because of physical differences among individuals.
An image-capturing device 414 shown in FIG. 25 has a fingertip guide 412 erected at the rear of the sensor unit 406, which fingertip guide 412 is provided to allow a user to bring his or her fingertips into contact with the fingertip guide 412 to locate the palm at the image-capturing position on the sensor unit 406. The image-capturing device 414, however, has a disadvantage that the positioning sensor guide 408 and the fingertip guide 412 project out of the image-capturing device 414, and that the palm may not be set at an optimum position even if the wrist is kept supported on the sensor guide 408 or the fingertips are brought in contact with the fingertip guide 412 because of physical differences among individuals.
As described above, various devices for positioning or settling have been devised to take a proper image of a person's hand free to move. For a portable device, especially, the above guide members are improper for installation. This leads to a problem that obtaining a detected image coinciding in position with a recorded image while both a portable device and a person's hand are free to move, is troublesome work.
No disclosure or hint has been presented to solve such a problem, and Patent Application Laid-Open Publication Nos. 2001-326841 and 1999-47119 disclose or hint no solution to the problem, either.